Photomechanical process of engraving.



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PHOTOMECI'IANICAL PROCESS OF ENG-RAVIING.

To all whom 'it may concern:

Be it known that I, HENRY L. RECKARD,-

a citizen of the United States, residing at Hartford, county of Hart-ford, State of Connecticut, lhave invented certain new and useful Improvements in Photomechanical Processes of'FingraVing, of which the following is a full, clear, and exact description.

My invention relates to photo-mechanical engraving of designs having modulations of light and shade, and consists in a simple and `accurate method of producingsuch engravsent continuous shadings or modulations.

Fig. 2 is a dry plate photographic negative of Fig. 1, the modulations here also being shown by shade lines for the reasons above stated. Fig. 3 is a wet plate negative of Fig. 2, made through a suitable screen by means of a camera, the result being a wet plate dotted positive of Fig. 1. Fig. l is a. lithographie stonehaving a lithograph made thereon'from the plate of-Fig. 3. Fig. 5 is a transfer made from the stone of Fig. 4,

trimmed down so as to correspond with the.

design of Fig. 1. Fi 6 is a zinc plate to which the'transfero Fig. 5 has been applied and subsequently removed so as to leave theink thereon, and which has been subsequently treated as hereinafter described. Fig. 7 represents a roller to be engraved, about to be rolled over the zinc plate so as to of Fig. 6 after the saine has been etched.

The following description will refer mor In Figs. 3, 4, 5 and 6, the dimensions of the vdots and the s aces between them, in order to ermit of i lustration, are enlarged, e greater than they would be in practice, as will be understood by those familiar with the use of half tone and similar screens.

In carrying` out the invention, the original of the design to be engraved must show the Specilcation of Letters Patent. Patentigd J 219 jg, Application led October 5, 1909.

Serial No. 521,147.

in Fig. l. Y Such original may be a Wash drawing, acolored picture or print orl a photograph, preferably afwash drawing 1 on white paper 2. My process is adapted to modulated printing in one color or modulated printing in several superimposed colors. f f

When the design is to be printed in one color, a dry plate photograph 3 (Fig. 2) is modulations as represented by the shade lines l first made, that is, a negative of the original design. A dry plate is used because t re produces more accurately the modulations of the original design. From that dry plate negative photograph a wet plate positive 4 (Fig. 3) is made through a suitable screen by means of a camera, the preferred form of screenbeinf a dotted screen in whichy small round dots located very close to one another appear clear and transparent, the field.

around the dots being opaque. The ordinary half-tone screen, however, may be used. A positive made with a dotted screen will show the design and all its modifications of light and shade ,in opaque dots A of varying sizes as in Fig. 3 and I term this dotted the photograph. By means of this ositive photograph I produce a photolithograph (Fig. 4) upon a stone or similar photolithographic surface 5 in the ordinary manner. From this photolithogra h I produce a transfer 6, (Fig. 5) or, if t e design is to be repeated upon the surface to be engraved, a number of transfers equal to the number of repeats necessary. I then apply to the transfer, or, if the designs are to be repeated, the transfers suitably mounted on a sticking up sheet, a thin sheet of zinc B (Figs. 6 and 7), preferably about 1/100 of an inch thick. I then remove the transfer paper in the ordinary way used in lithography, leaving the ink upon the zinc sheet. I then etch the sheet. In etching I first roll the zinc sheet with an inked roller until the .inked portions become-strong and sharp,

and then powder it with line asphalt. I then dust it clean with cotton or a brush, preferably cotton. I then warm it until the asphalt is melted into the ink, forming a hard sni'ooth acid resist. I then coat the exposed edges C and back of the zinc Isheet with aspha t varnish, except a space about 1./16 of an inch at the beginning of the design corresponding to the space D. I then immerse the zinc plate in dllute nitric acid.,`

about 1G parts of water to one part of nitric ositive awa v to a depth o so t at -it may be acid, untilthe ex" surfaces are eaten f.) about'2/1000 of an inch,

inked with an acid resisting ink applled with a smooth ink roller.

surface and de ths of the late.` It is a ty P p heldesi n to not a planographic surface.

` be en raved on theroller is in thede t s of resist and asphalt are washe ate. After etching the late, t e acid off with turthen cut off at E on a or end of the dethe p ntine. One edge' is ine with the remote edge sign( The plate is then inked'with a stiff paper in arallel with the edge or beginnlng of the esign vand about 1/16 ofA an mch away Y* rest for the roller, and

.sticky ink ,holds the pa from the design, being outside the etched line D which was not varnished. The r in lace. The onto t e stri of a perfectly c ean pressure applied. The roller H is then cause to revolve, rolling over the surface ofthe inked plate, and the ink is thereby transferred from the plate to the surface of the roller. The desi n shows in clean co per dots on the roller, t e field around the esign and around the dots being covered with acid-resisting ink'. The roller` is next etched. In doing this it is powdered with fine asphalt powder applied with soft cotton, and t en dusted clean with a clean piece of cotton. The asphalt adheres to the inked parts but does not adhere to the clean copper. The roller is then warmed from the inside until the asphalt blends with the ink. When cool the roller is immersed in a bath of acid, being continually rotated to assure an even actlon. I prefer to use as an etching solution chlorid of iron two parts, water one part. The etching solution eats out the exposed dots, leaving the design engraved in intaglio dots of varyingsize. After etching, the roller is cleaned and is ready `for intaglio printing.

When it is desired to engrave ro 1ers for roller H is then lowere paper G, which `provides multi-color printing in two ormore superimposed colors, the original must be a colored picture or printing. Three colors are ordinarily'used 1n such printing, in accordance with the well-known three color proc-` ess; In carrying out my invention 1n connection with such work three dry tri-color platenegatives are made through color lters, one negative for red, one for yellow and one for lue. From each ofthese negatives a wet plate positive is made througha suitable screen, preferably the form of dotted screen before described, although a halfthe edge of the table,

. 5 The etchin must be of such depth that the. Iinking ro er will deposit no' ink in the red color and blue co or.

, the various colors. an

in the original design by yulations of llght an 'Y `tettone tne screen may 1 be these positives a roller is en aved in the 4 same manner as-hereinbefore escribed. By'

these rollers, when in' proper alinement, the printing is done,v the proper rollers being urnished respectivel with yellow color, These colors are delivered by the rollers onto the fabric, one color -over the other, roducing a icture in shades of covor shown means of the blending in varying proportions of the three primary colors. Instead of transferring the ink from the transfers to the zinc sheet and then to the roller, it may be transferred directly from the transfers to the roller to be is preferable, however, to transfer it through the medium of the zinc sheet, since by so doing a permanent copy of the design read to be app trou le is obtained, and further, if b chance the ink is rubbed or other accident appens so as to render the design as impressed upon the roller imperfect before it 1s engraved, `the zinc sheet canl be readily cleaned and re'- inked, with the expenditure of much less time vand labgr than is necessary to make new transfers, and particularly to makev new transfers and stick them up in proper relation upon a lay-out. I

What I claim is:

1. In a photo-mechanical process of engraving metal, the improvement which consists in photographin' a desi having modulations of-light an shade means of a dry plate, photogra hing the esign carried by said dry late t rough a screen and obtaining there y a dotted positive of the origina, roducing a photo-lithograph from sal from said photo-litho aph, transferring the ink from said trans er to a metal surface and etching said metal surface, inking said metalv sur ace and transferring the ink used. From each of lied to the roller with little' engraved. It

otted positive, producing a transfer .l

therefrom to a metal roller and'etching saidA ymetal roller.

2. In a photo-mechanical process of engraving metal, the improvement which consists in photographin a desi having modshade y means of a dry plate, photographing the design carried by said dry p ate through a screen upon a wet plate, and obtaining thereby a dotted ositive of the original, producing a photoithograph from said dotted posltive, producing graph, transferring the ink from said transer to a' metal surface and etching said metal surface, inkin said metal surface and trans-V therefrom to a metal rollerV ferring the in and etching said metal roller.

' 3. In a photo-mechanical process of engraving metal, the improvement which consists \in photographing a design having su:

a transfer from said photo ,litho,

perimposed colors and modulations of light and shade through color filters and by means of dry plates, photogra hing the designs carried by the several) dry plates through a screen upon wet plates, and obtaining thereby dotted positives thereof, producing a plurality of photo-lithographs one from each of said dotted positives, producing a transfer from each. of said photolithographs, transferring the ink from said 10 transfers to metal' surfaces and etching said metal surfaces, inking said metal surfaces, transferring the ink therefrom to metal rollers and etching said rollers.

. HENRY L. RECKARD. Witnesses:

WILLIAM A. LORENZ, WM. H. HoNIss. 

